Granular urea storage bin sizing

Posted in: , on 25. May. 2016 - 14:16

Hello everyone,

I have a question about the sizing (geometry) restrictions of storage bins. The problem is that my client wants me to size his granular urea circular storage bins. He has limited the overall height of bins to max. 8 m.

On the other hand, the qty. of bins are restricted. The required volume for each bin forced me to increase the diameter of bins (approx. 10 m). This geometry made the bin fat and short.

The client insists on the 8 m height limitation and qty. He is saying that petrochemical specs say that urea storage bins shall not have more than 8 m height to prevent degradation and fracture of granules.

Is there any who has some experiences about storage of granular urea and its storage requirements or restrictions ? Any reference? Any fact or operating plant?

The last thing came to my mind was designing a rectangular bin with two hoppers instead of circular bin.

Thank you in advance guys,

Here is some information about the issue:

Material: Granular Urea

Density: 720 kg/m3

Repose Angle=28

Required operational bin volume: 585 m^3

Overall Height (including hopper and cylinder section)=8 m

Bins Capacity

Posted on 13. Jul. 2016 - 12:47

Sticking to 10 M dia. bins, the client would need two bins that held the storage in 45% cones with either a conical top at 28 degrees to the horizontal, or have vertical walls 2.66 M high to a flat top to contain the repose quantity. These bins would have a total height approx. 7.7 M. and contain a volume of 300 M3 each. Note that such bins will essentially develop a funnel flow form of discharge therefore the residence time of some of the contents will be indeterminate if the bins are refilled before they completely discharge.

If the height restriction is to limit the impact stresses of granules falling from this height the damage could be reduced by fitting a small dispersing cone under the bin inlet. This would impart a radial component to the fall that would both reduce the maximum fall distance by landing the initial material higher on the conical face and disperse the flow stream to expose the constituent particles to a broader part and thereby offer more air resistance that when traveling in a concentrated stream.